AGPS : Base Station Triangulation Base station triangulation relies on measurements of time differences across wireless networks. AGPS uses network cell ID detection to approximate a device's position based on the coordinates of the base station it's currently using. Accuracy depends on network infrastructure (density of base station). Density is quite good in cities and GPS being not accessible from inside buildings,underground parking lots etc.
For this reason, AGPS and GPS are often used in combination.
